• Buy only extra-virgin olive oil.

• Olive oil is best when it’s fresh, so use it as soon as possible.

• It’s typical for olive oils to be made of a “field blend” of different varieties of olives grown in a region. But stay away from industrial blends, which combine oils from all over the Mediterranean. Such producers may, for example, boost the flavor of a cheap Tunisian olive oil with oils from Italy or southern Spain. You’ll have no idea the origin, handling or flavor of the olives.

• Look for a harvest date on the label. If there’s no harvest date, look for the “use by” date. The “use by” date is tricky because it’s 18 months from the time the oil was put in the bottle – and olive oil is not bottled instantly. The oil could already be 18 months old when it’s put in the bottle, and then add another 18 months to that “and you’re getting some pretty old oil,” Jenkins said.

• “Cold extracted” is a meaningless term on a label because all extra-virgin olive oil is cold extracted.

• Look for the “protected denomination of origin” designation, which will appear on the label as DOP for Italian oils, DO for Spain, PDO for Greece and AOC for France, and which offer extra assurance of good quality.

• Store olive oil in a cool, dark place and it will last for two years. After that, if it’s been properly handled, it will still be fine for certain uses, such as cooking.

• How old is too old? It depends on how the olive oil has been stored. Jenkins once found 4-year-old olive oil in her pantry, and she used it to fry the Thanksgiving turkey with great results.

• Spend a little more on your next bottle of olive oil. People spend $30 on a bottle of wine at a restaurant, Jenkins notes, and it’s gone in one evening. A $30 bottle of olive oil will last much longer and give more pleasure.

• Consider buying olive oil online at sites such as gustiamo.com or olio2go.com. Olive oils sold in supermarkets are “generally not great,” Jenkins said. In one Portland grocery store, Jenkins and her son each pulled down a bottle of the same Sicilian olive oil from a high shelf. One bottle was still green, but the other had turned yellow, which means that it had been stored under bright lights for too long. “It’s terrible to think these people work so hard to bring a prestigious product to market,” she said, “and then the purveyors just don’t treat it well.”

• For the same reason, do not buy olive oil in clear glass bottles.

• Chefs should consider putting someone in charge of handling and storing oils, just as they do with wines. Jenkins says she has been served rancid olive oil in numerous restaurants in both Italy and Maine. In one high-end Portland restaurant that she wouldn’t name, Jenkins said to the server who gave her rancid oil: “This olive oil is very interesting. Where does it come from?”

“The waiter said – I swear to God he said this – ‘It’s local, of course. Everything we serve here is local.’ ”

Jenkins wonders where all those olive trees are growing. “Somewhere around Kennebunkport, maybe?” she said, laughing.

– MEREDITH GOAD